#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<arpa/inet.h>
#include<sys/socket.h>
#include<pthread.h>
#define BUF_SIZE 100
#define MAX_CLNT 256

void *handle_clnt(void *arg);
void send_msg(char *msg,int len);
void error_handling(char *msg);
int clnt_cnt=0;
int clnt_socks[MAX_CLNT];
//访问全局变量clnt_cnt和数组clnt_socks的代码将构成临界区
pthread_mutex_t mutx;
//多个客户端之前可以交换信息的简单的聊天程序
int main(int argc,char *argv[])
{
	int serv_sock,clnt_sock;
	struct sockaddr_in serv_adr,clnt_adr;
	int clnt_adr_sz;
	pthread_t t_id;
	if(argc!=2)
	{
		printf("Usage:%s<port>\n",argv[0]);
		exit(1);
	}
	pthread_mutex_init(&mutx,NULL);
	serv_sock=socket(PF_INET,SOCK_STREAM,0);
	
	memset(&serv_adr,0,sizeof(serv_adr));
	serv_adr.sin_family=AF_INET;
	serv_adr.sin_addr.s_addr=htonl(INADDR_ANY);
	serv_adr.sin_port=htons(atoi(argv[1]));

	if(bind(serv_sock,(struct sockaddr*)&serv_adr,sizeof(serv_adr))==-1)
		error_handling("bind() error");
	if(listen(serv_sock,5)==-1)
		error_handling("listen() error");
	
	while(1)
	{
		clnt_adr_sz=sizeof(clnt_adr);
		clnt_sock=accept(serv_sock,(struct sockaddr*)&clnt_adr,&clnt_adr_sz);
		
		pthread_mutex_lock(&mutx);
		clnt_socks[clnt_cnt++]=clnt_sock;
		pthread_mutex_unlock(&mutx);
		
		pthread_create(&t_id,NULL,handle_clnt,(void*)&clnt_sock);
		pthread_detach(t_id);
		printf("Connected client IP:%s\n",inet_ntoa(clnt_adr.sin_addr));
	}
	close(serv_sock);
	return 0;
}
void *handle_clnt(void *arg)
{
	int clnt_sock=*((int*)arg);
	int str_len=0,i;
	char msg[BUF_SIZE];
	//一直在读数据，直到客户端退出，那么就删除clnt_socks中的那个客户端套接字
	while((str_len=read(clnt_sock,msg,sizeof(msg)))!=0)
		send_msg(msg,str_len);
	pthread_mutex_lock(&mutx);
	for(i=0;i<clnt_cnt;i++)
	{
		if(clnt_sock==clnt_socks[i])
		{
			while(i++<clnt_cnt-1)
				clnt_socks[i]=clnt_socks[i+1];
			break;
		}
	}
	clnt_cnt--;
	pthread_mutex_unlock(&mutx);
	close(clnt_sock);
	return NULL;
}
void send_msg(char *msg,int len)//发送信息
{
	int i;
	pthread_mutex_lock(&mutx);
	for(i=0;i<clnt_cnt;i++)
		write(clnt_socks[i],msg,len);
	pthread_mutex_unlock(&mutx);
}
void error_handling(char *msg)
{
	fputs(msg,stderr);
	fputc('\n',stderr);
	exit(1);
}
